This invention is generally relative to a multiband Multiple-Input-Multiple-Output (MIMO)-based Wideband Code Division Multiple Access (W-CDMA) and Ultra Wideband (UWB) Communications for wireless and/or local-area wireless communications.
A MIMO is a multiple-input-multiple-output as a wireless link and is also a space-time signal processing. In the space-time signal processing a natural dimensional of transmitting data is complemented with a spatial dimension inherent in the use of multiple spatially distributed antennas. Thus this leads that the MIMO is able to turn multipath propagation into benefit for a user. In a MIMO system, signals on the transmit antennas and the receiver antennas are integrated in such a way that a quality of bit error rate (BER) or a data rate of the communication for each user or a transmitting distance is improved, thereby increasing a communication network's quality of service.
The next-generation wireless communication is defined to allow a subscriber to access World Wide Web or to perform file transferring over packet data connections capable of providing 144 kbps and 384 kbps for a mobility, and 2 Mbps in an indoor environment. The W-CDMA is a wideband, spread spectrum radio interface that uses CDMA technology to meet the needs for the next-generation wireless communication. The W-CDMA (also known as CDMA2000) supports for a wide range of radio frequency (RF) channel bandwidths from 1.25 MHz to 15 MHz operating at 1.90 GHz band, where the channel sizes of 1, 3, 6, 9, and 12×1.25 MHz. A wide channel of the W-CDMA offers any combination of higher data rates, thereby enhancing total capacity. The W-CDMA also employs a single carrier and a multicarrier system, which can be deployed as an overlay over one or more existing the second generation of TIA/EIA-95B1.25 MHz channels. In a multicarrier system, modulation symbols are de-multiplexed onto N separate 1.25 MHz carriers. Each carrier is spread with a 1.2288 Mcps chip rate.
With regard to the UWB communications, U.S. Federal Communications Commission (FCC) released a revision of Part 15 of Commission's rules for UWB transmission systems on Apr. 22, 2002. FCC permitted the marketing and operation of certain types of new products, incorporating UWB technology. Thus, UWB communication devices can operate using spectrum occupied by existing radio service without causing interference. This results permitting scarce spectrum resources to be used more efficiently. The UWB communication devices can offer significant benefits for Government, public safety, businesses and consumers under an unlicensed basis of an operation spectrum.
FCC is adapting unwanted emission limits for the UWB communication devices that are significantly more stringent than those imposed on other Part 15 devices. For an indoor UWB operation, FCC provides a wide variety of the UWB communication devices, such as high-speed home and business networking devices under the Part 15 of the Commission's rules subject to certain frequency and power limitations. However, the UWB communication devices must operate in the frequency band ranges from 3.1 GHz to 10.6 GHz, and have an emission of −10 dBm for the indoor UWB operation. In addition, the UWB communication devices should also satisfy the Part 15.209 limit for the frequency band below 960 MHz. Table 1 lists the FCC restriction of the emission masks (dBm) along with the frequencies (GHz) for the UWB communication devices in an indoor environment.
TABLE 1Frequency (MHz)EIRP (dBm) 0-960−41.3 960-1610−75.31610-1990−53.31990-3100−51.3 3100-10600−41.3Above 10600−51.3
The UWB communication devices are defined as any devices where a fractional bandwidth (FB) is greater than 0.25 based on the following formula:
                              FB          =                      2            ⁢                          (                                                                    f                    H                                    -                                      f                    L                                                                                        f                    H                                    +                                      f                    L                                                              )                                      ,                            (        1        )            where fh is the upper frequency of −10 dBm emission point, and fL is the lower frequency of −10 dBm emission point. A center transmission frequency Fc of the UWB communication devices is defined as an average of the upper and lower −10 dBm emission points as follows:
                              F          C                =                                                            f                H                            +                              f                L                                      2                    .                                    (        2        )            Furthermore, a minimum frequency bandwidth of 500 MHz must be used for indoor UWB communication devices regardless of the center frequency.
The UWB communication devices can be designed to use for wireless broadband communications within a short-distance range, particularly for a very high-speed data transmission suitable for broadband access to networks in the indoor environment.
A multiband MIMO-based W-CDMA and UWB communication transceiver system is disclosed herein according to some embodiments of the present invention. The invention system includes a W-CDMA base station, a UWB base station, and P-user dual-mode portable stations of W-CDMA and UWB communication devices. The W-CDMA base station has a multicarrier for 12 channels with a total of 15 MHz frequency bandwidth at the center of 1.9 GHz frequency band, and employs four antennas at the transmitter and receiver. The UWB communication base station uses a multicarrier for four frequency bands (referred to as a multiband) with a total of 2.048-GHz frequency bandwidth in the frequency range from 3.1 GHz to 5.15 GHz, and also employs four antennas at the transmitter and receiver. Each of the frequency bands in the UWB communications has a 512-MHz frequency bandwidth, using an Orthogonal Frequency Division Multiplexing (OFDM) modulation. On the other hand, each of the P-user dual-mode portable stations of the W-CDMA and UWB communication devices uses two antennas, and shares some of common components, such as analog-to-digital (A/D) and digital-to-analog (D/A) converters, memory, etc. The W-CDMA in the dual-mode portable stations uses 12 channels with each channel of 1.25 MHz, has a multicarrier, and is able to transmit a data rate more than 2 Mcps, while the UWB employs four frequency band-based multicarrier OFDM with each frequency band of 512 MHz, and can transmit a data rate up to 1.5872 Gbps. In addition, all of the dual-mode portable station use a direct sequence spread spectrum (DSSS), which is a pseudorandom (PN) sequence to spread a user signal. The DSSS is used to separate signals coming from multiuser. Thus, multiple access interference (MAI) among multiuser can be avoided when a set of PN sequences is designed with as low cross-correlation as possible.
An OFDM is an orthogonal multicarrier modulation technique that has its capability of multifold increasing symbol duration. Increasing the number of subcarriers in the OFDM modulation, the frequency selectivity of a channel may be reduced so that each subcarrier experiences flat fading for the UWB communications. Thus, an OFDM approach is a particular useful for the UWB communications over a short-range fading channel.
The present invention of the multiband MIMO-based W-CDMA and UWB communications utilizes both benefits of W-CDMA wireless phones and UWB wireless broadband communications. Such a dual-mode device not only can transmit the packet data in a form of wireless phone but also can use as a very-high speed wireless broadband Internet device to transmit and receive data, image, video, video game, music, and stock graph, etc., in a real-time. Thus, there is a continuing need of the multiband MIMO-based W-CDMA and UWB communication transceiver system for delivering a very-high data rate with a capability of flexibility and scalability in a combination form of the wireless and fixed wireless environment.